System and method for preservation, transport, and analysis of water samples

ABSTRACT

A device for collecting contaminants from water samples is provided. The device includes a solid sorbent that collects and stores the contaminants from water samples. The solid sorbent is configured to allow for the preservation of the stored contaminants. The concentrations of the contaminants in the water samples are determined via analysis of the solid sorbent or via elution of the stored contaminants from the sorbent and analysis of the eluate solution.

PRIORITY INFORMATION

This application is a divisional application of U.S. application Ser.No. 15/497,761 filed Apr. 26, 2017, which claims priority to U.S.Provisional Application No. 62/327,503 filed Apr. 26, 2016, the contentsof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention is related to the field of water quality monitoring, andin particular the invention describes technology to enable water samplesto be preserved in a compact form that is suitable for storage and/ortransport to centralized laboratories for chemical, microbial, or otheranalysis.

The safety of drinking water is judged by its physical, chemical, andmicrobial characteristics. Drinking water must be free of pathogens,contain low levels of toxic chemicals, and be tasteless, odorless, andcolorless. Water quality is assessed in terms key parameters forbiological contamination, where coliform bacteria is used as a proxy forfecal contamination; physical contamination, by use of parameters suchas turbidity and pH; and chemical contamination, where acceptable limitsare specified for contaminants such as arsenic, fluoride, nitrate,pesticides, and heavy metals such as lead, nickel, and copper. Many ofthese contaminants, such as arsenic and heavy metal contamination, occurnaturally, whereas other contaminants such as nitrate and pesticidesresults from human activities.

Water quality monitoring is typically performed using field test kits,mobile/local laboratories, or more centralized government or commerciallaboratories. Field tests provide rapid results with minimal training,but the accuracy, throughput, and sample processing ability in the fieldis limited. On the other hand, centralized laboratories are relativelyexpensive and often involve transportation of significant volumes (e.g.250 to 1000 milliliters (mL)) of water over long distances to urbanareas where these laboratories are located. This poses majordifficulties on the ability to acquire water quality data. For example,field testing to quantify low levels (<100 micrograms per milliliter(μg/mL)) of arsenic contamination is cumbersome, and contaminants likemercury, lead, cyanide need to be analyzed in the laboratory. Testingfor all the major types of pathogens is impossible in the field and evenin the laboratory; instead, total coliform bacteria are measured as aproxy indicator of fecal contamination. Field tests providepositive/negative or semi-quantitative results, and testing incentralized laboratories is required for accurate analysis. Thesechallenges place major limitations on the ability to acquire waterquality data and involve considerable fieldwork.

Although similar problems of water quality exist in many other parts ofthe world, these challenges are exemplified in the case of India.India's drinking water problems are grave in terms of both availabilityas well as quality. While increasing the volume of water available fordrinking and other domestic consumption is not the focus of thistechnology, it should be noted that according to India's National RuralDrinking Water Program (NRDWP), 30% of India's habitation get less than40 liters (L) per capita per day (lpcd), the amount required to maintainacceptable level of individual health and sanitation. Added to this arethe problems of water quality, which is our focus here. Out of India's11,274,819 documented sources of drinking water, by the year 2013-14,water quality testing data was available for only 1,734,882 (15.38%)(see http://indiawater.gov.in/IMISReports). Of the tested sites, 8% werefound contaminated with chemical, bacteriological, or other contaminantsbeyond acceptable levels set by the NRDWP. Much of this contamination isattributable to sources of water, as 77% of India's population obtainsits drinking water supply from sources other than piped water such ashand pumps, tube and dug wells, tanks, ponds, springs, canals, andrivers. The most vulnerable 10-14% population is reported to drink fromuncovered and untreated water sources.

India recognizes water as a public good and access to safe water fordrinking, cooking and other domestic as well as livestock use as afundamental right. It employs an elaborate regulatory machinery for theprovision, security, and safety of water that includes roles andresponsibilities at national, state, district, sub district, and villagelevels. The regulatory framework also defines a role for healthcareworkers, NGOs, and public-private partnerships. That being said,however, the demand for water quality management far exceeds the shearcapacity for testing samples, and the resources and knowhow of the localcommunities to deal with the results of such testing. The NRDWP reportsconfess that for the skeleton infrastructure of Water TestingLaboratories available at the district level, it is simply impossible tomeet the overall need to test the total 0.5 million water samples eachyear, if India were to meet the set target of once a year chemical andtwice a year bacteriological test.

One of the key challenges in meeting this target is that accuratequantification of many contaminants requires analytical equipment whichis not cost-effective to deploy at the sub-district level where routinetesting occurs. In particular, trace contaminants such as arsenic, heavymetals, and pesticides require quantification via methods such as atomicadsorption spectroscopy (AAS), inductively coupled plasma-opticalemission spectroscopy (ICP-OES), inductively coupled plasma-massspectrometry (ICP-MS), or gas chromatography-mass spectrometry (GC-MS)in order to accurately detect contamination at their acceptable limits.These analytical instruments are present in state laboratory facilities,but require more capital investment and technical expertise than isavailable for district and sub-district laboratories. As a result,routine testing frequently quantifies only those contaminants which canbe detected using the methods available at the district and sub-districtlevel, with limited ability to identify harmful levels of thosecontaminants which require analytical equipment that is only availableat the state level.

When one considers these constraints for India and other locations, oneuse case which would benefit for improved sampling technology is thecollection of samples at local laboratories in a manner which makes themeasy to transport to centralized laboratories with more advancedanalytical equipment. While this is difficult to do with full-sizedliquid samples due to their weight and the need for additional sampleprecautions such as acidification and/or temperature control, theability to store contaminants in a solid matrix would facilitate easiertransport between laboratories via methods such as the postal service.In addition to transfer between labs, the ability to store contaminantsin a compact solid matrix would facilitate storage within laboratoryfacilities so that samples taken over time can be analyzed at a laterdate if the need emerges. This utility has already been demonstrated formedical diagnostics through the use of dried blood spot (DBS) testing,where blood samples are dried on a paper matrix, sent to centralizedtesting and storage facilities, and can be analyzed for small moleculesand pathogens for as long as ten years. This ability to analyze samplesof drinking water or other fluids at a different time or place wouldprovide benefit to analytical applications in drinking water,environmental monitoring, and other applications.

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided a device forcollecting and releasing contaminants from water samples. The deviceincludes at least one solid sorbent that is capable of adsorbing targetcontaminants, preserving the target contaminants for extended periods oftime, and releasing the target contaminants for subsequent analysis.Means for supporting or containing the at least one solid sorbent andfacilitating rapid adsorption of the contaminants is provided. A packagestores the at least one solid sorbent with adsorbed contaminants.

According to another aspect of the invention, there is provided a devicefor collecting and releasing contaminants from fluid. The deviceincludes at least one solid sorbent that adsorbs and releases targetcontaminants. Means for supporting or containing the at least one solidsorbent and facilitating rapid adsorption of the contaminants isprovided. A package stores the at least one solid sorbent with adsorbedcontaminants.

According to another aspect of the invention, there is provided a methodof collecting and releasing contaminants from water samples. The methodincludes providing a water sampling device having at least one solidsorbent, and exposing the device to a sample of water. Also, the methodincludes allowing the at least one solid sorbent to adsorb one or morecontaminants from the water, and removing the device from contact withthe water. Furthermore, the method includes releasing the one or morecontaminants from the at least one solid sorbent at a later time, andperforming analysis on the released contaminants.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic diagram illustrating a foldable container structureused in accordance with the invention to collect contaminants;

FIG. 2 is schematic diagram illustrating a tea bag arrangement used inaccordance with the invention to collect contaminants;

FIG. 3 is schematic diagram illustrating an impregnated rigid orflexible materials accordance with the invention to collectcontaminants;

FIG. 4 is schematic diagram illustrating a packed bed geometryarrangement used in accordance with the invention to collectcontaminants;

FIG. 5 is a graph illustrating the adsorption isotherms of copper oncellulose, from experiments in which copper at various concentrationsfrom 0.025 mg/L to 5 mg/L was adsorbed from 30 mL of pH buffereddeionized water using 0.15 g GE Whatman Grade 1 Qualitative filterpaper;

FIGS. 6A-6B are scanning electron microscopy (SEM) images illustratingthe granular morphology and surface morphology of iron oxide xerogels,where the xerogels are synthesized via epoxide-assisted gelation using ametal chloride precursor (either iron(III) chloride hexahydrate oraluminum(III) chloride hexahydrate) dissolved in ethanol before theaddition of an epoxide (propylene oxide), followed by gelation anddrying at room temperature for 18 days before sputtering with gold andimaging via SEM;

FIG. 7 is a graph illustrating the Barrett-Joyner-Halenda (BJH) poresize analysis of iron oxide and alumina xerogels, where the xerogels aresynthesized via epoxide-assisted gelation using a metal chlorideprecursor (either iron(III) chloride hexahydrate or aluminum(III)chloride hexahydrate) dissolved in ethanol before the addition of anepoxide (propylene oxide), followed by gelation, five solvent exchangesin ethanol, drying for at least seven days at room temperature, anddrying for three days at 130 degrees Celsius (° C.) to remove anyresidual moisture before BJH analysis via nitrogen adsorption anddesorption;

FIG. 8 is a graph illustrating the adsorption isotherms of arsenic(III)on iron oxide xerogel at neutral and basic pH values, from experimentsin which arsenic(III) (in the form of sodium arsenite) at variousarsenic concentrations from 0.05 mg/L to 500 mg/L was adsorbed from 30mL samples (with pH values modified via the addition of sodiumhydroxide) onto iron oxide xerogels with sorbent masses from 23 to 102mg (average mass 51 mg) over an adsorption period of at least 24 hours;

FIG. 9 is a graph illustrating the recovery of copper, nickel and leadfrom DOWEX G-26 ion exchange resin (commercially available from DowChemical Company) after dry storage for up to 4 months. Various amountsof resin, from 0.5 g to 3 g of resin were contacted with 250 L of waterwith 400 mg/L or 3200 mg/L total dissolved solids and 0.250 mg/L each ofcopper, nickel and lead. After adsorption, resin was blotted dry andallowed to dry at room temperature. After a certain time of dry storage,cations were eluted from the dry resin samples using 5 or 10%hydrochloric acid and the concentration of recovered cations wasmeasured using ICP-OES

FIG. 10 is a graph illustrating the recovered arsenic concentration as afunction of the initial arsenic sample concentration for iron oxidexerogels adsorbing arsenic(III) at neutral pH and desorbing the sampledarsenic at high pH, where arsenic(III) (in the form of sodium arsenite)was adsorbed from 30 mL samples onto iron oxide xerogels with sorbentmasses from 38 to 61 mg (average mass 48 mg) over an adsorption periodof at least 20 hours, dried and stored at room temperature for 12 to 34days, and eluted from the dry xerogel samples via desorption into 30 mLof 0.1 molar (M) sodium hydroxide solution over a desorption period of24 hours, with initial and recovered concentrations quantified viaICP-MS;

FIGS. 11A-11B is a table and graph illustrating the adsorption kineticsof copper onto DOWEX G-26 cation exchange resin contained in differenttea bag geometries made of propylene meshes and flexible epoxy adhesive.After fabrication, bags were held stationary in 250 mL of stirring waterwith hardness 400 mg/L and 0.250 mg/L each copper, nickel and lead.Samples of solution were removed over the course of the experiment andthe samples were analyzed using ICP-OES to generate concentration versustime curves for comparison of tea bag performance.

DETAILED DESCRIPTION OF THE INVENTION

The invention describes a water quality monitoring paradigm usingsampling technology, materials, and system-level protocols to enable drysample preservation of water samples to facilitate easyambient-temperature shipping, storage, and rapid processing atcentralized laboratories to greatly improve the ability to monitor thewater quality. The ability to easily store and ship water samples hasthe potential to open a new paradigm in water quality management. Drywater sample preservation techniques described here are expected tofacilitate easy shipping, storage, and rapid chemical and microbialanalysis of water quality in centralized laboratories.

Several approaches can be conceived for dry preservation of watersamples. Commercially available dried blood spot (DBS) sorbents alreadyused for chemical and microbial analysis in human blood samples could beapplied to water sample analysis. Custom-designed sorbents could also beused for this purpose. For example, membranes or porous media can befunctionalized with positive charge using polyethyleneimine to bindnegatively-charged bacteria when water is flushed through. In addition,high-surface-area inorganic morphologies such as silica or metal-oxidexerogels frequently present charged sites that may change charge with pHand redox conditions. Also, polymers containing stationary chargedgroups, such as ion exchange resins, can be used to adsorb positively ornegatively charged species over a wide range of pH conditions. Watersamples that are preserved in dry (or compact) state can then beanalyzed using existing laboratory-based chemical and microbial analysismethods.

The key consideration in chemical preservation is to ensure aquantitative relationship between the concentration of analytes inoriginal water sample and the laboratory results from the preservedsample. On one hand, strongly adsorbing sorbents may be used tofacilitate concentration of the chemical during filtration across thesorbent. On the other hand, sorbents can provide a surface for chemicalsto precipitate or crystallize out when water evaporates.

The water sample to be analyzed is flowed through or contacted by aporous sorbent, where the porosity and dimensions of the sorbent aredesigned to ensure adsorption of the analytes of interest. It iswell-known that the amount of analyte that can be adsorbed will dependon the nature of the sorbent, total surface area of the sorbent, volumeof weight of the sorbent, volume of the water sample, concentration ofthe analyte, pH, and any competing species in the water sample. Agreater amount of sorbent or greater surface area of sorbent will resultin greater amount of analyte adsorption. Furthermore, the diffusion andadsorption kinetics of the analyte will influence the amount adsorbed.Therefore, the porosity and dimensions (e.g. thickness or cross-sectionarea) of the sorbent can be tuned to control the flow rate (for example,driven by gravity) and the sorbent surface area to achieve rapidadsorption. Examples of sorbents include cellulose (including filterpaper) and surface modified cellulose (including cellulose nitrate andamidoximated cellulose), synthetic polymers such as polyamide,polyacrylamide and polyacrylonitrile, cation or anion ion exchangeresins made of polystyrene-divinylbenzene or polyacrylic acid, chitinand chitosan, zeolites, mineral clays, lignin, xerogels with metal-oxideor silica backbone, activated carbon, carbon nanotubes, and compositesof these materials.

As an explicit example of these sorbents, FIG. 6A-6B shows the granularmorphology and surface morphology of iron oxide xerogels, as imaged byscanning electron microscopy (SEM). Xerogels are high surface area,nanoporous materials which can be easily and cheaply synthesized fromprecursor salts via epoxide-assisted gelation. Surface area and poresize distribution of fabricated iron oxide and alumina xerogels can bedetermined using Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda(BJH) analysis, as shown in FIG. 7 . The surface area of the fabricatediron oxide xerogels is 330 square meters per gram of xerogel (m²/g),while the alumina xerogels have a surface area of 460 m²/g.

In many cases, complete adsorption of the analyte or analytes ofinterest can be desirable, but in some cases partial adsorption can besufficient provided that it is consistent and a calibration can beestablished to relate the analyte concentration in the water sample tothe amount adsorbed. Furthermore, given that certain conditions such aspH can affect analyte adsorption, chemicals (e.g. buffer) may be addedto the water sample or incorporated into the device or sorbent tofacilitate adsorption. Additionally, sensors that measure pH, turbidity,conductivity or other parameters may be incorporated in the device toprovide additional information for device operation and monitoringpurposes. Other mechanisms that are known to promote adsorption ofdifferent species on surfaces can also be used; for example, it iswell-known that charged species can be adsorbed on electrodes under theapplication of an electric potential, such as that used in capacitivedeionization method for water desalination. In some cases, sorption insolids or liquids (which may be encapsulated in a matrix in the form ofdroplets) can be used instead of surface adsorption. For example,hydrophobic organic species in water can preferentially partition intooil or into some polymeric substances such as poly(dimethyl siloxane).Alternatively, adsorption (or sorption) may be achieved by immersing asorbent material into a water sample, with or without stirring, for asufficiently long period of time.

After adsorption is completed either by flowing the water samplethrough, by immersion, or any other means, the sorbent can be dried, orthe residual water sample can be discarded, while retaining the desiredanalyte(s) on or in the sorbent. The sorbent may or may not be dried toremove water, stored, or transported to a different location. It isnoted that the weight or volume of the sorbent (and any device thesorbent can be incorporated in) is less than that of the original watersample. By selecting materials with high adsorption capacities, theamount of sorbent needed for sampling is minimized. For example,commercial filter paper can adsorb 0.6 milligram (mg) copper per gram(g) of filter paper, as shown in FIG. 5 , whereas cation exchange resinscan exchange 2 moles of charge per liter of resin, which corresponds todifferent amounts of heavy metal cations depending on their charge. Dueto their high surface area, iron-oxide xerogels reliably adsorb highamounts of arsenic at neutral pH (pH=6-9), with arsenic capacities ashigh as 120 mg per g xerogel sorbent, as shown in in FIG. 8 , As aresult, heavy metal cations from a 1 L water sample can be preserved ona sorbent such as a filter paper weighing 1 g to 10 g or ion exchangeresins weighing 0.2 g to 10 g. Arsenic can be preserved from a 1 L watersample using xerogels weighing 0.1 g to 5 g. To retrieve the originalconcentration of analyte(s), the sorbent can be directly analyzed usingmethods that accept the sorbent without further processing (e.g. X-rayFluorescence (XRF), X-ray Photoelectron Spectroscopy (XPS),graphite-furnace atomic absorption spectroscopy (GFAAS), laser ablationmass spectrometry (LA-MS), laser-induced breakdown spectroscopy (LIBS),or elemental analysis following chemical and/or microwave digestion.

Alternatively, the analytes can be released into water or any liquidsolution with controlled or known composition, so as to avoidinterference with the analyte concentration measurement, such asdeionized water, nitric, hydrochloric or sulfuric acid solution, orsodium hydroxide solution, with the desorbed analytes then quantified byuse of methods such as ultraviolet/visible spectroscopy, flame atomicabsorption spectroscopy (FAAS), ICP-OES, and ICP-MS. Examples ofdesorption methods include acidic pH dissolution of the sorbent (e.g.filter paper in nitric acid), acid pH elution (e.g. ion exchange resinsin hydrochloric or nitric acid) or use of a pH where adsorption is nolonger favorable (e.g. use of high-pH solutions such as sodium hydroxideto desorb anions from iron-oxide xerogels). For example, at least 80% ofthe amount of copper, lead or nickel adsorbed to ion exchange resins canbe recovered from the sorbent after up to 4 months of dry storage atroom temperature, as shown in FIG. 9 . Similarly, the amount of arsenicrecovered from iron-oxide xerogels after adsorption at neutral pH anddesorption at high pH (by use of 0.1 M sodium hydroxide) follows aconsistent power-law relationship over the entire concentration range ofinterest for drinking water samples (up to 5000 ppb) after dry storageperiods of as long as 34 days at room temperature, as shown in FIG. 10 .The amount or concentration of the analyte(s) measured by these methodscan then directly correlate with the analyte concentration in theoriginal water sample, or it can be related to the concentration of theanalyte in the original water sample using calibration.

Similarly, dry or compact preservation of microbial contaminants canenable (1) direct culture of microbes for analysis and (2) nucleic acid(DNA/RNA) analysis. The process can involve concentration of themicrobes by filtration or stirring and adsorption, or the use of celllysis media to extract and adsorb nucleic acids or other biomolecules.For example, lysing the cells followed by filtering through aDNA-binding sorbent may be used to extract DNA and store it on thesorbent. The DNA can be released for analysis. Such sorbents andconditions to elute (remove) nucleic acids and other molecules areknown, for example, for sorption and elution of DNA on silica.

Alternatively, bacteria can be captured using positively chargedsorbents or filtered through a porous sorbent and the captured cells canbe lysed (burst) before DNA analysis; for example, microbes could becaptured in hydrogel matrices which facilitate their survival withoutallowing appreciable growth, such as methods that have been previouslyused for human cells. DBS cards and kits available for nucleic acidextraction and preservation may be adapted for analysis of watersamples; for example, the FTA card marketed by GE Healthcareincorporates chemicals to lyse (burst) cells and bind their DNA, whichcan be preserved in dry state and is eluted upon exposing the card towater. Similarly, filtering or sorption may be used for preservingviable E. coli that can be cultured after dry or wet storage in a volumeor weight that is smaller than that of the original sample.Preservatives may be added to the water sample or on the sorbent. Forexample, trehalose is a suitable preservative that retains highviability of E. coli after air-drying.

Materials for preservation of water samples can be integrated intocost-effective, easy-to-use devices that can be implemented for watermonitoring paradigm in large-scale deployments.

Sorbents are molded into a geometry or contained in a device, whosegeometry is optimized for fast contaminant absorption kinetics, fordevice operation time on the order of 10 minutes or less. Optimalgeometries for rapid uptake may differ depending on the sorbent and sodifferent geometries may be used for different sorbents. Additionally,any material used in the device must be compatible with the entireadsorb/store/release protocol. For example, kinetics of copper uptake onion exchange resins contained in polypropylene tea bags are negativelyaffected by the particle size of ion exchange resin; however, theopening size of the polypropylene mesh does not affect the kineticssignificantly with all copper adsorbed within 10 minutes, as shown inFIGS. 11A-11B.

These devices should include the capability for collection of aprescribed volume of water, and reuse for repeated collections withoutcross-contamination. This includes use of containers with set or markedvolumes, and a disposable sorbent that may be removed from the containerand shipped to a laboratory for analysis, with a new sorbent insertedfor the next water sample. The sorbent can include filter paper,xerogels, polymers, or composites. Also, the sorbent can be of the formof a packed-bed cartridge containing sorbent granules, a cartridgecontaining the sorbent coated onto a monolithic structure such as ahoneycomb for well-defined flow, a rigid wafer consisting of a porousmatrix impregnated with sorbent particles, a rigid wafer consisting of aporous matrix coated with a conformal layer of sorbent, a membraneconsisting of a flexible matrix (such as paper or fabric) coated with alayer of additional sorbent, or a membrane consisting of a flexiblematrix (such as paper or fabric) impregnated with sorbent (as particlesor a coating), where the shape of the flexible matrices may bemaintained during sample collection and shipping via a rigid supportaround the edges of the flexible matrix.

The inventive device includes the active sorbent material, which takesup the contaminants from solution, and any supporting structurenecessary for device operation and maximum interaction between thesorbent surface and sample solution. The device can include multiplesorbents, each specific for the uptake of a specific contaminant orclass of contaminants (for example, cationic, anionic, and organiccontaminants). The sorbents may be mixed together, or they may bemodularly contained to allow for detachment of one type of sorbent andseparate storage, transport, release, and/or analysis of eachcontaminant. All materials contained in the device are compatible withthe entire sampling and preservation protocol.

The device is contained in clean packaging, such as an envelope or smallthin box. When ready for use, the user removes the device from thepackaging and applies the water sample to the device following anestablished protocol for the specified time. The device may then beblotted of excess water using clean absorbents and/or dried at roomtemperature, after which the device is deposited back in the original orspecifically provided packaging for clean long term storage and/ortransportation. Additionally, if the device does not need to be driedprior to storage and/or transportation, the device may be directlydeposited in the appropriate packaging without drying or blotting.

FIG. 1 shows a foldable container 2 that can be compacted for transport,shipped in an envelope, or fold into a shippable container itself usedas a dry sampling device. Here, the container 2 (or other structure,e.g. a sheet or spiral) can be placed in a first configuration 4, suchthat a larger surface area is exposed to the water during the collectionstep. In the first configuration 4, the exposed area to the waterincludes a solid sorbent 8 used to collect contaminants. Then, thecontainer 2 would be transformed to a second configuration 6 aftersample collection encapsulating the sorbent 8, such that its includedvolume is substantially smaller than the first configuration 4 andtherefore is more suitable for transport to a second location such as acentralized testing facility. Embodiments of such a container 2 includea paper ‘cell’ which can collapse to a near-flat packing; a creasedsheet (e.g., a miura-ori pattern) that can be unfolded into a containercontaining water and then folded for transport. Therefore, thetransformable element 6 can also form the sample collection and capturecontainer itself, or comprise a section of a container into which it isplaced. Another embodiment would flow the water of other solution overand/or through the foldable element during the capture phase, andoptionally later during the release phase.

FIG. 2 shows a tea bag arrangement 12 used in accordance with theinvention. A tea bag 12, encloses the sorbent material 14. The tea bag12 is fabricated from layers of plastic mesh or fabric 16, which areglued, melted or sewed together into a bag structure of an optimizedgeometrical shape that retains flexibility. The tea bag 12 may befabricated from chemically inert materials such aspolytetrafluoroethylene (PTFE) or polypropylene (PP) so that contaminantadsorption and release occurs consistently from the sorbent matrix 14alone. The tea bag 12 can be either a free-standing structure, or have ahandle or loop, which aids the user in using the tea bag to capture thecontaminants. A single tea bag can contain multiple compartments fordifferent sorbents.

In some embodiments, the sorbent support has a rigid or flexible handle,a string, or other mechanism of holding that enables the sorbent to beimmersed, stirred in, or exposed to the water, such that the fingers ofthe operator do not touch the sorbent or the water sample and causecontamination.

FIG. 3 shows an impregnated rigid or flexible materials arrangement 20used in accordance with the invention. Impregnated rigid or flexiblematerials, in which the sorbent 32 is contained in the structure of theporous supporting material. Deposition of the sorbent material isachieved through direct chemical reaction, inclusion of the sorbentmaterial during supporting material synthesis or adhesion using anappropriate adhesive. Supporting materials include synthetic filtrationmembranes, and filter paper sheets. The supporting material can alreadybe in the desired geometry (such as a filter paper disk) prior todeposition, or the entire impregnated material can be synthesized inbulk and cut or molded into the desired geometry post synthesis, such asa fibrous brush, woven mat or porous monolith.

FIG. 4 shows a packed bed geometry arrangement 36 used in accordancewith the invention. The packed bed geometry arrangement includes a layer38 of sorbent that is contained between two porous supports 40, 42 in acylindrical or rectangular geometry. The packed bed 36 can includemultiple layers of sorbents, which can be taken apart and dried,transported and processed separately.

The sorbent material can include coated structures, such as plasticmeshes, porous strips, fabrics, cotton or synthetic fibers, porousmonolithic structures or honeycombs. The materials to be coated may bein their desired form prior to being coated or be coated in bulk,allowing for manipulation of the coated material into the desiredgeometry after processing, such as a fibrous brush or woven mat.

Also, the sorbent materials can be formed into other high-surface-areastructures. The sorbent material makes up the majority of the device,such that these devices may or may not have significant supportingmaterial, unlike the other embodiments aforementioned. Sorbents, such aspolymers or xerogels, may be formed into structures during synthesis ormolded/formed into a structure after synthesis. Examples include sorbentpolymer fibers or films that are woven into a mat or fabric, or cut intoshort sections and fused together at one end in a brush format; polymersor xerogels that are cast into a mesh mold during synthesis; andmaterials that are melted and extruded into different geometries throughelectrospinning or 3D printing. These high-surface-area structures canconsist solely of the sorbent material, or of composite materialsincorporating the sorbent and other materials (such as chitosan or otherpolymers) which confer flexibility, toughness, or other desiredmechanical properties to the structure.

Application of the water sample to these devices may occur throughprocesses such as 1) flow of solution through the device, 2) flow ofsolution over the device, 3) stirring the device within the watersample, or 4) static adsorption by placing the device within thesolution or the solution within the device. Additional supportingequipment necessary to using the sorbent can be included with theoriginal packaging. Examples include rigid outer supports for sorbentimpregnated, coated or formed membranes, foldable flow-throughapplication systems in a cup or box form for use of flow through or flowover geometries (such as membranes or meshes) and a handle or frame formaterials to be rigidly supported while being stirred with watersamples.

Moreover, the invention provides the capability for filtering andspatially defined deposition of chemical and bacterial contaminants fromthe prescribed volume of water may be achieved by use of differentsorbents in the same device connected to a single or multiple watercontainers within the device. The amount of water sampled by eachsorbent may be controlled by appropriate choice of resistance to fluidflow (pressure divided by fluid flow rate) for the fluid flow pathwayscorresponding to each sorbent. A single-use sample collection “card” canbe used by the invention, which receives the filtered/depositedconstituents and can be mailed by post or the like. Also, there shouldbe a requirement for only simple text or graphical instructions, andoffering visual confirmation of successful use, and ease of distributionand collection of the samples. The invention could be fabricated usingenvironmentally sustainable materials, and using local manufacturingcapacities.

In other embodiments of the invention, the inventive device can includeat least one of a pH sensor, a salinity sensor, a turbidity meter, achromogenic sensor, or other kinds of sensor. Moreover, the time framewhen removing the inventive device from the water to the analysis canrange from 7-30 days. In addition, it can take between 3 and 15 minutesfor the sorbent to absorb one or more contaminants from the water.

The invention reduces the cost and time limitations imposed bytraditional water quality monitoring, by stably preservingcontaminations in a compact and/or dry form, which can be shipped to theadvanced labs using the existing postal service structure and associatedfees. Dry preservation enables the transport of samples from a range ofdistances to advanced laboratories, allowing more water sources can beaccurately analyzed for complete contaminant arrays using standardanalytical techniques, potentially increasing the monitoringcapabilities and reach of centralized bodies. Additionally, analysisprotocols developed with the dry preservation technology complement theexisting standard analytical procedures, so that the dry samplingtechnology aids the existing system.

Although the present invention has been shown and described with respectto several preferred embodiments thereof, various changes, omissions andadditions to the form and detail thereof, may be made therein, withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A method of collecting and releasing at least onetarget contaminant from a water sample, a volume, V, of the water samplepicked as follows: 250 mL≤V≤1 L, the method comprising: providing awater sampling device having at least one solid sorbent, wherein the atleast one solid sorbent comprises a plurality of particles, and whereinsize of each of the plurality of particles is picked to influenceadsorption kinetics of the at least one target contaminant when thewater sampling device is inserted in the water sample, wherein the sizeof the plurality of panicles are picked to be within the followingrange: 300 μm-650 μm; exposing the device to the water sample; allowingthe at least one solid sorbent to: (1) adsorb the at least one targetcontainment, (2) preserve the at least one target contaminant forextended periods of time, and (3) release the at least one targetcontaminant for subsequent analysis, wherein the at least one targetcontaminant is preserved in a compact or dry form, wherein aconcentration, C, of the target contaminant is in the following range: 0mg/L<C≤0.25 mg/L, the plurality of particles having size 300 μm-650 μmadsorbing all of the target contaminant within 20 minutes; removing thewater sampling device from contact with the water sample; releasing theat least one contaminant from the at least one solid sorbent at a latertime; and performing analysis on the released at least one contaminant.2. The method in claim 1, wherein the device is packaged for storage ortransportation before the release step.
 3. The method as in claim 1,wherein the device dries after the removal step and before the releasestep.
 4. The method as in claim 1, wherein the duration between theremoval step and the analysis step is at least 24 hours.
 5. The methodas in claim 1, wherein the duration between the removal step and theanalysis step is at least 7 days.
 6. The method as in claim 1, whereinthe duration between the removal step and the analysis step is at least30 days.
 7. The method in claim 1, wherein the at least one solidsorbent comprises at least one of an ion exchange resin, xerogel, orcellulose.
 8. The method of claim 1, wherein the device is stored in apackage to prevent contamination.
 9. The method in claim 1, wherein theone more contaminant is adsorbed by manually stirring the device in thewater sample.
 10. The method in claim 1, wherein the one or morecontaminants are adsorbed by flowing the water sample through thedevice.
 11. The method in claim 1, wherein the one or more contaminantsare adsorbed by immersing the device in the water sample.
 12. The methodin claim 1, wherein the one or more contaminants are released by flowinga release solution through the device.
 13. The method in claim 1,wherein the one or more contaminants are released by immersing thedevice in a release solution.
 14. The method of claim 1, wherein the oneor more contaminants adsorption step requires less than 15 minutes. 15.The method of claim 1, wherein the one or more contaminants adsorptionstep requires less than 3 minutes.
 16. The method in claim 1, whereinthe device is transported to another location after adsorption forstorage or analysis.
 17. The method in claim 16, wherein the device istransported via the postal service or a commercial shipping service. 18.The method in claim 1, wherein the device is stored at the same locationafter adsorption for analysis at a later date.
 19. A method ofcollecting and releasing at least one target contaminant from a fluidsample, a volume, V, of the fluid sample picked as follows: 250 mL≤V≤1L, the method comprising: providing a fluid sampling device containingat least one solid sorbent, wherein the at least one solid sorbentcomprises a plurality of particles, and wherein size of each of theplurality of particles is picked to influence adsorption kinetics of theat least one target contaminant when the fluid sampling device isinserted in the fluid sample, wherein the size of the plurality ofparticles are picked to be within the following range: 300 μm-650 μm;exposing the device to the fluid sample; allowing the at least one solidsorbent to: (1) adsorb the at least one target containment, (2) preservethe at least one target contaminant for extended periods of time, and(3) release the at least one target contaminant for subsequent analysis,wherein the at least one target contaminant is preserved in a compact ordry form, wherein a concentration, C, of the target contaminant is inthe following range: 0 mg/L<C≤0.25 mg/L, the plurality of particleshaving size 300 μm-650 μm adsorbing all of the target contaminant within20 minutes; removing the fluid sampling device from contact with thefluid sample; releasing the at least one target contaminant from the atleast one solid sorbent; and performing analysis on the released atleast one target contaminant.
 20. A method for collecting and releasingat least a first target contaminant and a second target contaminant froma water sample, a volume, V, of the water sample picked as follows: 250mL≤V≤1 L, the method comprising: (a) providing a water sampling devicefabricated from a mesh or a fabric, the water sampling comprising atleast a first compartment and second compartment; (b) providing a firstsolid sorbent enclosed within the first compartment, the first solidsorbent capable of adsorbing a first target contaminant; (c) providing asecond solid sorbent enclosed within the second compartment, the secondsolid sorbent capable of adsorbing a second target contaminant; (d)exposing the water sampling device to the water sample; (e) allowing thefirst solid sorbent enclosed within the first compartment to: (1) adsorbthe first target contaminant, (2) preserve the first target contaminantfor extended periods of time, and (3) release the first targetcontaminant for subsequent analysis, wherein the first targetcontaminant is preserved in a compact or dry form, wherein a firstconcentration, C1, of the first target contaminant is in the followingrange: 0 mg/L<C1≤0.25 mg/L; (f) allowing the second solid sorbentenclosed within the second compartment to: (1) adsorb the second targetcontaminant, (2) preserve the second target contaminant for extendedperiods of time, and (3) release the second target contaminant forsubsequent analysis, wherein the second target contaminant is preservedin a compact or dry form, wherein a second concentration, C2, of thesecond target contaminant is in the following range of 0 mg/L<C2≤0.25mg/L; (g) removing the water sampling device from contact with the watersample; (h) releasing the first and second target contaminants from thefirst and second solid sorbents at a later time; and (i) performinganalysis on the released first and second target contaminants; whereinthe first solid sorbent comprises a first plurality of particlesenclosed within the first compartment, and wherein size of each of thefirst plurality of particles is picked to influence adsorption kineticsof the first target contaminant when the device is inserted in the watersample, wherein the second solid sorbent comprises a second plurality ofparticles enclosed within the second compartment, and wherein size ofeach of the second plurality of particles is picked to influenceadsorption kinetics of the second target contaminant when the device isinserted in the water sample, wherein the size of the first plurality ofparticles or the size of the second plurality of particles are picked tobe within the following range: 300 μm-650 μm, and the first plurality ofparticles of size 300 μm-650 μm in the first compartment adsorbing allof the first target contaminant within 20 minutes and the secondplurality of particles of size 300 μm-650 μm in the second compartmentadsorbing all of the second target contaminant within 20 minutes. 21.The device of claim 20, wherein openings in the mesh are picked to bewithin the following range: 150 μm-400 μm.
 22. The device of claim 20,wherein either the first solid sorbent or the second solid sorbent is anion-exchange resin.
 23. The device of claim 20, wherein the mesh is anyof the following: a polypropylene (PP) mesh or a polytetrafluoroethylene(PTFE) mesh.